1. Field of the Invention
The present invention relates to a current-mode driver for powering different light sources in a backlight system.
2. Description of the Related Art
Inverter controllers for driving lamps typically regulate the voltage across each lamp and any series-connected ballast capacitor or inductor. The voltage regulation technique makes striking the lamp and regulating the lamp current difficult to achieve without costly and complex circuitry. For example, a lamp driver typically includes a starting algorithm that is different from steady state operations to light the lamp. The starting algorithm usually runs at a higher frequency and uses strike detection circuits that complicate the lamp driver design. Furthermore, gas discharge lamps have a negative resistance characteristic, and the lamp driver typically needs some degree of resonance to achieve sufficient high impedance for smooth operation after striking the lamp. Tuning the lamp with shunt capacitance across primary or secondary windings of an output transformer in the lamp driver is common.